Let’s say you are living in the moment, feeling giddy — a little tipsy, maybe — and you decide to go for it. You decide to get that tattoo.

Dr. Suzanne Kilmer has a warning for you: Think twice before acting. Not only do you face five times the risk of contracting hepatitis C, chances are you’ll change your mind about whether you like your tattoo before you reach middle age.

Kilmer, 55, a clinical professor at the University of California-Davis, has seen tattoo-regret galore.

“Most people come in and say, ‘It was something I did while I was young, and I’ve outgrown it,’” Kilmer said.

The founder of the Laser & Skin Surgery Center of Northern California, she’s removed upward of 20,000 of the inky images.

That’s no small accomplishment, and Kilmer is no ordinary dermatologist. It’s something of a well-kept secret in Sacramento that in Kilmer the region has a world-renowned, pre-eminent expert in the field of laser tattoo removal and laser skin care.

To this day, Harvard University mentors who first worked with Kilmer as a fellow in the 1990s describe her as a pioneer in tattoo removal — and a force who has helped chart the future of the field.

“She actually had a hand in the very early development of lasers for tattoo removal,” said Dr. R. Rox Anderson, professor of dermatology at Harvard University.

Kilmer also is known for creating a world-class laser center that does groundbreaking research for U.S. Food and Drug Administration clinical trials and as the only woman to have headed the American Society for Lasers in Surgery and Medicine.

But in the realm of tattoo removal, Kilmer’s work has opened up possibilities for better and faster results — key in a nation filled with people obsessed with etching on their outermost organ.

Removal is difficult, lengthy and painful. Think hot bacon grease spattered on the skin. Think the sting of a stretched rubber band smacking you from up close. Imagine paying $150 to $1,000 for the multiple appointments to obliterate a tattoo.

People “have no idea how hard it is to get it off,” Kilmer said of tattoo dye.

Among those who find themselves at her east Sacramento clinic are job seekers, career professionals and parents of young kids who seek to erase stigma, Kilmer said. There are former gang members and people with what’s termed “traumatic tattoos” identifying them, for example, as former prisoners of war.

Brittany Costarella, 38, was in the laser chair one recent day, trying to rid her midriff of a winged, haloed red heart. It wasn’t her first time there.

“Oh my gosh, if people knew how painful it is to get it off,” Costarella said. “It feels like piercing hot oil. Not a hot oil droplet, but deep heat under the skin.”

Lasers deliver hot, powerful pulses through the upper skin to a deeper layer where a tattoo artist has embedded pigment.

When the laser beam hits a particle of ink, its force fractures the pigment. Immune system cells then move in to clean up the mayhem, which the body’s lymphatic system clears away.

One hopes, that is.

Some tattoos leave “ghosts” behind that simply will never disappear even after several rounds of the laser beam.

Melissa Leal, 30, a doctoral student in Native American studies at the University of California-Davis, was undergoing her ninth removal appointment one sunny April afternoon.

She had a silver nose ring, silver hoop earrings about the diameter of a soda can and a short bob of hair dyed as red as an apple. The tattoo on her ankle she didn’t mind, but the swirl of blue-black curlicues on the back of her hand - that had to go.

As Leal was zapped, she looked away, grimaced and practiced deep breathing.

“What she’s feeling is the heat breaking up the ink dye,” Kilmer said. “Usually, if it hurts, it means it’s working.”

On this spring day with birdsong and blossoms in the air, an unusual sense of excitement charged the atmosphere inside the J Street complex.

About a dozen laser technology professionals crowded a hallway while awaiting the West Coast’s first demonstration of a new, state-of-the-art picosecond machine.

That one-of-a-kind device delivers laser pulses at the rate of one-trillionth of a second, as opposed to a nanosecond machine, the industry standard, which pulses at the slower one-billionth of a second.

The new machine in the corner of the room was built by a colleague at Kilmer’s request. A previous picosecond model she’d tested at Lawrence Livermore Laboratories 20 years ago was the improbable size of a small barn.

“This is just what I asked for,” Kilmer said. “I’ve literally waited about 18 years for this. It took that long to figure out the science of sizing it down.”

Unlike other skin-care centers in the Sacramento region, Kilmer’s houses 30 to 40 different generations and types of lasers, said Kathy Keys, who works with Kilmer as a registered nurse.

Even under Kilmer’s supervision, tattoo removal can be a challenge. For each tattoo, each patient is diagnosed, charted, treated, educated and observed by Kilmer with the utmost attention to skin type and pigment of tattoo ink.

Kilmer has written scientific papers about which lasers work best with certain colors and types of ink.

She also warns the public of potentially hazardous components in ink — chromium, cobalt, cadmium, mercury, titanium dioxide and more.

The other day she was examining a blue butterfly ankle tattoo that had grown lighter in shade with each laser treatment but was still stubbornly recognizable.

“We need to tell people that light blue is the worst color you can choose,” said Kilmer. “It’s definitely the hardest ink to remove.”

Kilmer or a trained technician will take a couple of passes at a tattoo within one treatment session, allowing the skin to rest about 20 minutes in between.

But if the first laser treatment puffs the skin into a raised welt — as happened to the James Brown lyrics on patient Richard Cumings’ neck recently — Kilmer will wait eight weeks before the next treatment to allow the skin to recover.

Several patients and colleagues said in interviews that one of the qualities they appreciated most in Kilmer was her carefully conservative approach to laser skin care.

Cumings, 35, is a longtime admirer of Kilmer. He recalled that two decades earlier, she had removed for free a gang tattoo from his cheek — “NS” for North Sacramento — when he was a juvenile in custody for robbery.

Since then, and a stint in prison that he finished with barbed wire tattooed on his wrist (“I cover that one up with my watch”), he’s worked hard at making better choices, he said.